1. Field of the Invention
The present invention pertains generally to the field of fiber board containers and is more particularly directed to improvements in corrugated cardboard boxes capable of being collapsed or extended along one dimension of the box.
2. Description of the Prior Art
While a great deal of inventive activity has taken place in connection with packaging materials and in particular with folded cardboard containers and boxes, this applicant is not aware of prior art directly pertinent to the concept described and disclosed below. U.S. Pat. No. 4,559,259 to Cetrelli discloses a packing laminate creased for folding into a container and provided with auxiliary crease lines adjacent to the intersection of two crease lines where the laminate material is subjected to special stresses and is thus prone to crack.
The concept of providing auxiliary crease lines to relieve stress at a primary fold line is well-known in the art, as exemplified for example, by U.S. Pat. No. 4,586,650 to Sasaki et al. which likewise provides auxiliary creases at an intersection of fold lines in containers for liquids. The auxiliary creases relieve stresses at the corners of the containers to prevent formation of cracks or pinholes and consequent leaking of the contents.
U.S. Pat. Nos. 1,758,230 and 1,482,569 to Lange disclose a corner edge or joint in a cardboard box which is formed by means of multiple crease lines including one arrangement where crease lines are formed on opposite sides of the cardboard to facilitate folding. A similar approach is taken in U.S. Pat. No. 3,526,566 to MacIlvain, Jr., et al. for folding thick paper board sheets. U.S. Pat. No. 3,899,120 to Fradkin suggests the step of crushing paper board along well-defined selected areas which permits the use of slits in the cardboard instead of wider slot cutouts in the manufacture of otherwise conventional cardboard boxes.
U.S. Pat. No. 4,284,227 issued to Corey shows an expansion file folder having an accordion pleated backbone but which, however, is devoid of any corners transverse to the direction of the fold and thus does not overcome the difficulties encountered in multi-dimensional accordion folds such as would be required to allow extension or collapse of a cardboard container having intersecting wall panels and where the extension and collapse occur in a direction parallel to the lines of intersection of these wall panels.
A need exists for such collapsible boxes, particularly such boxes made of corrugated cardboard for products which do not completely fill the container during storage and shipment but which in use require an oversize container. This, for example, is the case with litter boxes for house pets where the litter material fills only a fraction of the cardboard box. In actual use it is desirable for the walls of the litter box to rise substantially above the litter material to contain and keep the litter material from being displaced from the box by the pets. However, for purposes of shipping, storage and sales-on-shelf purposes, it is undesirable for the box to be full height due to space restrictions and inherent weakness due to the empty top space in the partly filled box so that the weight of stacked boxes is not carried by the litter filling but must instead be borne by the box walls.